In recent years, as a network such as the internet has become widespread and the number of users thereof has increased, advertisements have been vigorously inserted on communication site screens and the like that are read through the network, and a large number of proposals regarding an advertisement distribution system have been made (e.g. Patent References 1 to 5).
Further, there has been proposed a mechanism in which an advertisement associated with a search keyword is displayed in a specific section on a Web page in a search engine and the like of the internet. In this mechanism, on the precondition that the user who conducts search has a keen interest in a keyword that he or she has inputted, advertisement information associated with the keyword is provided. Moreover, in this mechanism, an advertisement distributing side initially determines a bid price for each keyword, and an advertisement displaying order is determined in accordance with the heights of the bid prices.    [Patent Reference 1]: Japanese Patent Laid-Open No. 2001-236444    [Patent Reference 2]: Japanese Patent Laid-Open No. 2002-7462    [Patent Reference 3]: Japanese Patent Laid-Open No. 2002-56280    [Patent Reference 4]: Japanese Patent Laid-Open No. 2002-366834    [Patent Reference 5]: Japanese Patent Laid-Open No. 2003-16334